This invention relates to an automatic bar feeding apparatus for feeding long bar stock material automatically into a machine tool, particularly a numerically-controlled automatic screw machine or a lathe.
In recent years, there has been a demand for ever increasing speeds of main spindles and for ever improving precision in machining in numerically-controlled automatic screw machines or automatic lathes, numerically-controlled lathes, and the like which are automatically controlled.
In these machine tools, machining of bar material is frequently carrried out, and in these times of intensive trend toward automation and unmanned operations, it is the general practice to carry out the feeding of bar material for machining by means of an automatic bar material feeding apparatus.
In the machining operation of these machines of cutting the bar material, however, there arise several causes of impairment of machining precision at the time of cutting such as the noise of rotation of the bar material, vibration due to action of transverse vibration accompanying the bar rotation, and chattering due to inadequate gripping by the spring collet.
Particularly the greatest factor impeding the increases in speed and improvements in precision of these machines in the machining of bars is the motional behavior of the rotating bar material undergoing machining.
Accordingly, in order to increase the machining speed and improve the machining precision of these machines, an automatic bar material feeding apparatus to operate in conjunction with these machines is required to fully control the rotational behavior of the bar material affecting the machining precision thereof.